1. Field of the Invention
A pinch valve for modulating, throttling and curtailing or terminating the flow of a fluid.
2. Description of the Prior Art
Pinch valves basically consist of a flexible resilient cylindrical elastomeric sleeve of the like which is interposed in a continuous conduit, duct, pipe or tube, together with means to constrict the sleeve so as to curtail, terminate or control the flow of fluid through the conduit or the like. In most instances, the sleeve is concentrically oriented within an outer rigid valve housing, and means are provided to impress a fluid under pressure between the sleeve and the housing so that the sleeve is squeezed inwards and deformed or collapsed to provide a smaller fluid flow passage. In other instances, mechanical means are provided to pinch the sleeve to accomplish the same result. One problem encountered with pinch valves of the prior art is a tendency of the joints between the sleeve and/or the valve housing, and the continuous lengths of conduit or the like, to ultimately leak due to distortion of the sleeve and repeated flexing of the same.
Normally, a pinch valve sleeve is made from pure gum rubber, neoprene, BUNA, butyl, hypalon, urethane, viton, EPT (nordel), silicone and food grade rubber. Typically, any suitable flexible and resilient (and usually corrosion-resistant) material of construction may be employed for the sleeve. However, a synthetic rubber such as hypalon, BUNA, neoprene, a deformable plastic, or natural rubber are preferred. The flexible and resilient sleeve will in general be resiliently deformable and will be composed of any suitable material such as those mentioned supra. In this regard, it will be understood by those skilled in the art that any rubbery or rubber-like elastic material may be employed to fabricate the sleeve. Thus, hypalon is defined as a rubber material obtained by the chlorination and sulfonation of polyethylene. BUNA is defined as a rubber substitute prepared by the polymerization or copolymerization of butadiene. Neoprene is defined as polychloroprene made by the polymerization of chloroprene, i.e. neoprene is a generic name for synthetic rubber made by polymerization of 2-chloro-1,3-butadiene (prepared by the action of hydrogen chloride on monovinylacetylene).
Pinch valve constructions, as generally described herein, have been used in a wide variety of situations. More specifically, pinch valve constructions as described herein have been used in controlling the flow of, by way of example, solids in suspension (either in slurry or air-conveyed form), especially abrasive materials such as metallic ores, asbestos, fibers, sand, coal, sugar, wood chips or pulps, paper stock, plastic pellets, raw sewage, talc, cement, fly ash, and various chemicals and foodstuffs.
Among the prior art relating to pinch valve constructions may be mentioned U.S. Pat. Nos. 4,172,580; 4,125,125; 3,838,704; 3,483,892; 3,445,085; 3,441,245; 3,396,448; 3,371,677; 3,272,470 and 3,159,373; German Pat. No. 1,038,850; British Pat. No. 639,646 and Italian Pat. No. 535,034.